The latest British Intelligence report points out that the Russian Aerospace Forces (VKS) are using the Sukhoi Su-5 Felon 57th generation fighter against Ukraine since June 2022. Russia, however, is avoiding deploying its most modern aircraft within Ukrainian territory. 

The Su-57 made its first flight almost 13 years ago, when it was still called the T-50 PAK-FA. It is the country's first 5th generation fighter, as well as the only one of its kind in service and the only stealth aircraft in operation with VKS, which received its first production example in 2020.

Called Felon (criminal) by NATO, the Su-57 is Russia's most modern and advanced fighter. The model was even tested in combat in Syria in 2018, still in the prototype phase. While the plane's presence in the Middle East was highly publicized by Moscow at the time, the use of the Su-57 in the conflict in Eastern Europe followed a completely opposite path. 

In May, about three months after the outbreak of war, Russian state media already pointed to the use of the aircraft against Ukraine. However it was it was only in October that an official source acknowledged (and praised) the participation of the Su-57 in the so-called Special Military Operation (SMO). 

On the other hand, the UK Ministry of Defense (MoD) claims that VKS has been carrying out Felon missions in Ukraine since June, using long-range air-to-air and air-to-ground missiles against targets in the invaded country 10 months ago.

“Recent commercially available footage shows five Felons parked at Akhtubinsk Air Base, home to the 929th Flight Test Center. As this is the only known Felon base, these aircraft were likely involved in operations against Ukraine.”, says the folder. 

However, despite the clear superiority of the Su-57 compared to models used by Ukraine (MiG 29, Su-24, Su-25 and Su-27), the MoD claims that offensive flights by the Russian stealth fighter do not go beyond the limits of Russian territory.

“Russia is highly likely to prioritize avoiding reputational damage, reduced export prospects and the compromise of sensitive technology that would result from any loss of FELON over Ukraine. This is symptomatic of Russia's continued risk-averse approach to employing its air force in the war."

In other words, Russia uses the Su-57 in operations against Ukraine, but only within its own territory, without crossing the border, to avoid possible losses (and an eventual capture) of its most advanced vector. Logically it is more difficult for Ukraine to shoot down a Su-57 than a Su-35, for example, but it is not impossible. 

The MoD also cites the "compromise of sensitive technology” in case a Su-57 was shot down. In September, Ukrainian forces captured one of Russia's most advanced electronic warfare systems, found next to the wreckage of a Su-30 fighter shot down in March. This fact raised questions about Russia's possible negligence in cleaning up the aircraft's landing area to prevent sensitive equipment from falling into enemy hands. 

A possible shooting down of the Su-57 would only bring even more tribulations for Moscow, which has already gone through a hard time since invading Ukraine. As well as being a problem in terms of security, it would be a huge embarrassment for the Russians, whose performance in the war has been heavily criticized and seen as ineffective. 

Furthermore, Russia is still trying to sell the Su-57 to other countries, something that would be highly disfavored if the stealth plane was shot down in Ukraine.